Effects Of Different Grazing Intensities On Soil Organic Matter And Community Quantitative Characteristics In Desert Steppe

Desert grassland is one of the main grassland types in the central and western regions of the Inner Mongolia Autonomous Region.It is an important pastureland in Inner Mongolia and plays an important role in maintaining local animal husbandry production and ecological security.Grazing is the main method of grassland utilization.Long-term continuous overgrazing has caused vegetation degradation in the originally fragile desert grassland ecosystem,and land desertification has led to a significant decline in its ecological barrier function and productivity.However,different grazing intensities have an impact on grassland vegetation,soil and productivity.There are differences in impact.In order to explore the effects of grazing intensity on the community structure and organic matter in desert steppe,this paper took the desert steppe ecosystem in Sunite,Grassland Research Institute,Chinese Academy of Agricultural Sciences as the research object.Four grazing intensification(Light Grazing(LG),Medium Grazing(MG),Heavy Grazing(HG),and Extreme heavy Grazing(EG))were set with the closed no-grazing pasture as the control(CK).A completely random block test design was adopted to lay out the sample plots.Through the long-term grazing control experiment,using the quadrat investigation,unmanned aerial vehicle monitoring,indoor test and analysis method of combining the,under different grazing intensity,vegetation coverage and community characteristics of soil organic matter and its response to the grazing intensity,clarify VDVI vegetation index、NDVI vegetation index and ground quadrat investigation analysis of vegetation coverage,the difference of the order to desert grassland ecosystem health,the dynamic monitoring of grassland resources,rational utilization and scientific planning and management to provide basis and practice guidance.The main research results are as follows:(1)With the increase of grazing intensity,the organic matter content of each grazing plot had no obvious change trend.The results of spatial distribution of organic matter showed that the plots with the highest organic matter content were LG2 and MG3,and light to moderate grazing increased the content of soil organic matter.Elevation has a great influence on the content of organic matter.In low-lying areas,the content of organic matter is relatively high;otherwise,the content is relatively low.There was a negative correlation between the content of organic matter and the elevation of grazing plots,and the variation trend of the two was basically the same.(2)In the grazing area,the accuracy of vegetation extraction results based on VDVI is higher than that of NDVI,and the overall accuracy can reach 94.97%.Vegetation coverage decreased with the increase of grazing intensity,and it showed as the control area > Light Grazing > Medium Grazing > Heavy Grazing > Extreme heavy Grazing.CK control plot has no interference from external conditions,and the vegetation coverage distribution is more uniform.The values of vegetation coverage and organic matter near the water tank were all lower in each grazing community,and the vegetation coverage in the remote fenced area farther from the water tank was higher.The distribution trend of areas with higher vegetation coverage is consistent with those with lower elevation.(3)The importance value of perennial grasses increased with the increase of grazing intensity,but the importance value of annual herbs and biennial herb decreased with the increase of grazing intensity.With the increase of annual rainfall,the biomass of each experimental plot also increased significantly,especially in ungrazed and lightly grazed plots.The importance value of Allium ramosum and Allium mongolicum as good forage was the highest in CK plot and the lowest in EG treatment.(4)The diversity level of each experimental plot was low,and the diversity of vegetation community was different under different grazing intensities,but the difference was not significant.Light Grazing increased the α diversity index of the community,but with the further increase of grazing intensity,the biodiversity gradually decreased.